SYSTEM FOR THE FORMATION OF MICROSTRUCTURES IN POLYMERIC MATERIALS

Abstract

 The invention belongs to the field of materials science, more specifically, to the technology for the production of microstructures - the development of elements of microelectromechanical systems (MEMS). This system comprises a magnetostrictive vibrator (1) consisting of multilayer ferromagnetic plates, the operating part of which is attached to the concentrator-sonotrode (2, 4). Between the end parts of the magnetostrictive vibrator (1) the gasket (3) is installed that insulates the temperature and the liquid. The entire magnetostrictive vibrator (1) is housed in a sealed housing (9) with the coolant (10) circulating therein. The magnetic conductor plates of magnetostrictive vibrator (1) are wound with windings (6) and (7) comprising terminals which, like the signal from the temperature and vibration sensor (11) on the mechanical vibration concentrator (2, 4), are connected to the excitation and control generator (8). The operating part of the concentrator-sonotrode (2, 4) performs the forming procedure by applying pressure to the polymeric material (5) on the tray (13). The comprehensive and timely effect of high-frequency vibration excitation and increased temperature and pressure on the formed polymeric structure allows to increase the efficiency of the whole process and the quality of the structural elements to be produced.

Description

FIELD OF THE INVENTION

[0001] The invention belongs to the field of materials science. More specifically, to the technology for the production of microstructures - the development of elements of microelectromechanical systems (MEMS).

THE PRIOR ARTS

[0002] Currently, a method and an apparatus for the development of a MEMS sensor using thermal and mechanical pressure and high frequency oscillation excitation for this purpose is known (Amer Sodah, 2020, Development and analysis of microelectromechanical sensors for human health care monitoring. Doctoral dissertation, 106 p., p. 62). The specified device uses tightly interconnected piezoceramic rings with electrodes connected to a high frequency generator for excitation of oscillations. The piezoceramic rings are mounted in the structure of an electromechanical transducer (sonotrode), the working part of which has a heat-emitting source at the end. According to the established control program and in a certain time sequence, the microstructure is formed by pressing the sonotrode into the forming material, controlling the temperature regime and subjecting high frequency oscillations. The disadvantage of the specified prototype is that the dedicated device uses piezoceramic elements for excitation of oscillations, the operating temperature of which cannot exceed 180 °C, because at higher temperatures the piezoceramic elements depolarize, thus losing the piezoeffect. Adapting the temperature regime to mechanical pressure and high frequency oscillations over time is a complex process depending on the functionality of the control elements.

[0003] One of the most popular technologies for the production of MEMS elements is the formation of structural elements, which involves the gradual use of lithography, electroplating and micro-casting processes (Lin C H and Chen R 2006 Ultrasonic nanoimprint lithography: a new approach to nanopatterning J. Microlithgraphy, Microfabrication Microsyst, https://doi.org/10.1117/1.2172992).

[0004] The innovative chart for the production of MEMS elements presented in another document (Chi Hoon Lee, Phill Gu Jung, Sang Min Lee, Sang Hu Park, Bo Sung Shin, Joon-Ho Kim, Kyu-Youn Hwang, Kyoung Min Kim and Jong Soo Ko. 2010 Replication of polyethylene nano-microhierarchical structures using ultrasonic forming. Micromech. Microeng) shows the main structural and equipment elements, as well as stages for that process in the scale of time. As shown in Figure 9a of the document, the ultrasonic frequency generator excites mechanical oscillations at a frequency of about 20 kHz in an electromechanical transducer, and they are transmitted and amplified in an oscillation concentrator. The ultrasonic oscillations of the concentrator due to friction with the product in the contact zone generate relatively high energy, which makes high temperatures, which in particular is used to bond polymers or metals. This process takes place in a very short time (up to 3 s), is ecologically clean and economical. Figure 9b of the document shows the sequence of the whole process: after contact with the forming element, the clamping force of the polymer plate is increased to 690 N, and for some time it is stable and then the bonding of the surfaces takes place with the help of high-frequency oscillations. At that time, due to the friction of the surfaces, the molten polymer fills the nanostructured cavities and after some time the polymer hardens. In the specified device, the temperature required for the bonding of the surfaces is achieved due to friction excited by high-frequency oscillations between the surfaces to be bonded, which is difficult to achieve without a control system.

[0005] The invention eliminates the disadvantages of the prior arts - it solves the temperature regime coordination with the moment of pressure on the material to be formed and the high frequency oscillations with respect of time.

SUMMARY OF THE INVENTION

[0006] The invention is a system for forming microstructures in polymeric materials, comprising an electromechanical transducer - a magnetostrictive vibrator, a sonotrode, a generator, a clamping mechanism, and a tray with the material to be formed. The presented system generates high frequency oscillations in a magnetostrictive vibrator consisting of a magnetostrictor with a core on which two windings are wound: one for achieving the magnetization level of the magnetostrictor, and the other for excitation of the high frequency oscillations in the magnetostrictor. The magnetostrictor consists of a rectangular U-shaped magnetic conductor assembled from multilayer plates of metal (nickel, permalloy, or similar materials) whose U-shaped open edge is rigidly connected to a sonotrode made of bulk ferromagnetic-magnetostrictive metal. The magnetostrictor with windings is housed in a sealed housing in which the coolant circulates. The mechanical vibration concentrator-sonotrode is separated from the magnetostrictor with windings by a gasket to isolate temperature and liquid. After excitation in the magnetostrictor the high-frequency oscillations, they are transmitted to a high-frequency oscillation concentrator-sonotrode, which also heats up due to the circuital induction of the eddy currents. In this case, the vibration level of the sonotrode is being changed by an electrical signal from the magnetostrictor magnetization winding, while the sonotrode temperature is changed by a high-frequency electrical signal connected to the corresponding magnetostrictor winding. The vibration and temperature levels of the sonotrode are measured by a sensor attached to the sonotrode operating part. In this way, the operating part of the sonotrode, while vibrating and heated to set temperature, contacts the polymeric material to be formed and, according to a coordinated program, the forming process in the polymeric materials can be efficiently controlled from the single generator control unit.

DESCRIPTION OF DRAWINGS

[0007] The invention is explained in the drawings. The accompanying diagrams and drawings form an integral part of the description of the invention and are provided as a reference to a possible embodiment of the invention, but are not intended to limit the scope of the invention.

[0008] The system according to the invention and as shown in Figure 1 comprises the magnetostrictive vibrator (1) consisting of multilayer ferromagnetic plates, the operating part of which after closing the circuit of magnetic forces is rigidly attached to the mechanical vibration concentrator-sonotrode (2, 4). Between the end parts of the magnetostrictive vibrator (1) there is the gasket (3) that insulates the temperature and the liquid. The entire magnetostrictive vibrator (1) is housed in the sealed housing (9) with the coolant (10) circulating through the supply and discharge pipes (12). The magnetic conductor plates of the magnetostrictive vibrator are wound with windings (6) and (7) comprising terminals which, like the signal from the temperature and vibration sensor (11) on the mechanical vibration concentrator (2, 4), are connected to the excitation and control generator (8). The operating part of the mechanical vibration concentrator-sonotrode (2, 4) performs the forming procedure by applying pressure to the polymeric material (5) on the tray (13).

DETAILED DESCRIPTION OF THE INVENTION

[0009] The system for forming microstructures in polymeric materials shown in Figure 1 comprises the electromechanical transducer (vibrator) (1) consisting of a U-shaped rectangular ferromagnetic-magnetostrictive plates wound with windings (6) and (7) with free ends rigidly connected to the vibration concentrator-sonotrode (2, 4). One of the windings (6) is for the DC component generating the DC electromagnetic field necessary to control the amplitude of the mechanical oscillations, and the other winding (7) is for generating the high frequency AC electromagnetic field in the magnetostrictor and controlling the concentrator-sonotrode (2, 4) temperature which may rise due to circuital currents being excited therein. In the process of forming microstructures in polymeric materials, the electrical signal is applied from the generator of vibration excitation and controller (8) to one of the windings (6) that is intended to generate the DC electromagnetic field and control the amplitude of the mechanical vibrations, and the electrical signal is applied to the other winding (7) that is intended to generate the AC electromagnetic field and to control the temperature of the concentrator-sonotrode (2, 4). The electromagnetic field generated by the AC and DC windings (6, 7) in the ferromagnetic-magnetostrictive plates causes mechanical vibrations, which are transmitted to the vibration concentrator-sonotrode (2, 4) rigidly connected to the free ends of the magnetostrictive vibrator (1). The entire magnetostrictive vibrator (1) is housed in a sealed housing (9) with coolant (10) circulating therein through the liquid supply and discharge pipes (12), thereby protecting the magnetostrictive vibrator (1) from overheating. The coolant (10) is separated from the vibration concentrator-sonotrode (2, 4) by the gasket (3) that insulates temperature and liquid. In order for the whole system for formation of microstructures in polymeric materials to work stably and efficiently, the temperature and vibration sensor (11) is mounted on the operating part of the vibration concentrator-sonotrode (2, 4), the signal from this sensor being fed back to the excitation and control generator (8).

[0010] This comprehensive and timely effect of high-frequency vibration excitation and increased temperature and pressure on the formed polymeric structure allows to increase the efficiency of the whole process and the quality of the structural elements.

Claims

1. A system for forming microstructures in polymeric materials comprising an electromechanical transducer (1), a vibration excitation generator (8), and a high-frequency vibration concentrator-sonotrode (2), characterized in that the electromechanical transducer (1) comprises a U-shaped rectangular ferromagnetic magnetostrictive plates wound with windings (6, 7), the free ends of which are rigidly connected to a vibration concentrator-sonotrode (2) made of a bulk ferromagnetic-magnetostrictive metal.

2. The system according to Claim 1, characterized in that in the electromechanical transducer (1), a winding (7) powered by a high-frequency AC electrical signal from the vibration excitation generator (8) is used to control the temperature mode of the vibration concentrator-sonotrode (2).

3. The system according to Claim 1, characterized in that the winding (6) supplied with a DC electrical signal from the vibration excitation generator (8) is used in the electromechanical transducer (1) to control the vibration mode of the vibration concentrator-sonotrode (2).

4. The system according to Claim 1, characterized in that the vibration and temperature sensor (11) is attached to the operating part of the vibration concentrator-sonotrode (2), which is connected as feedback to the excitation and control generator (8).

5. System according to Claim 1, characterized in that a liquid-insulating gasket (3) is installed between the electromechanical transducer (1) and the vibration concentrator-sonotrode (2).

Amended claims

Amended claims in accordance with Rule 137(2) EPC.

1. A system of forming microstructures in polymeric materials comprising an electromechanical transducer (1), a vibration excitation and control generator (8), and a high-frequency vibration concentrator-sonotrode (2), wherein the electromechanical transducer (1) comprises a U-shaped rectangular ferromagnetic magnetostrictive plates wound with windings (6, 7), the free ends of which are rigidly connected to a vibration concentrator-sonotrode (2) made of a bulk ferromagnetic-magnetostrictive metal,
characterized in that in the electromechanical transducer (1), a winding (7) powered by a high-frequency AC electrical signal from the vibration excitation and control generator (8) is used to control the temperature of the vibration concentrator-sonotrode (2).

2. The system according to Claim 1, characterized in that the winding (6) supplied with a DC electrical signal from the vibration excitation and control generator (8) is used in the electromechanical transducer (1) to control the vibration of the vibration concentrator-sonotrode (2).

3. The system according to Claim 1, characterized in that the vibration and temperature sensor (11) is attached to the operating part of the vibration concentrator-sonotrode (2), which is connected as feedback to the excitation and control generator (8).

4. System according to Claim 1, characterized in that a liquid-insulating gasket (3) is installed between the electromechanical transducer (1) and the vibration concentrator-sonotrode (2).

Drawing